Spatially resolved charge-state and current-density distributions at the extraction of an electron cyclotron resonance ion source

Journal Article · Thu Sep 15 04:00:00 EDT 2011 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3637462· OSTI ID:22063711

Panitzsch, Lauri; Peleikis, Thies; Stalder, Michael; Wimmer-Schweingruber, Robert F ^[1]

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1. Institute for Experimental and Applied Physics (IEAP), Christian-Albrechts-Universitaet, Kiel (Germany)

In this paper we present our measurements of charge-state and current-density distributions performed in very close vicinity (15 mm) of the extraction of our hexapole geometry electron cyclotron resonance ion source. We achieved a relatively high spatial resolution reducing the aperture of our 3D-movable extraction (puller) electrode to a diameter of only 0.5 mm. Thus, we are able to limit the source of the extracted ion beam to a very small region of the plasma electrode's hole (O = 4 mm) and therefore to a very small region of the neutral plasma sheath. The information about the charge-state distribution and the current density in the plane of the plasma electrode at each particular position is conserved in the ion beam. We determined the total current density distribution at a fixed coaxial distance of only 15 mm to the plasma electrode by remotely moving the small-aperture puller electrode which contained a dedicated Faraday cup (FC) across the aperture of the plasma electrode. In a second measurement we removed the FC and recorded m/q-spectra for the different positions using a sector magnet. From our results we can deduce that different ion charge-states can be grouped into bloated triangles of different sizes and same orientation at the extraction with the current density peaking at centre. This confirms observations from other groups based on simulations and emittance measurements. We present our measurements in detail and discuss possible systematic errors.

• OSTI ID: 22063711
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 9 Vol. 82; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
APERTURES
BEAM EMITTANCE
BEAM EXTRACTION
CHARGE STATES
CURRENT DENSITY
ECR ION SOURCES
ELECTRODES
FARADAY CUPS
HEXAPOLES
ION BEAMS
MAGNETS
PLASMA
PLASMA SHEATH
SPATIAL RESOLUTION